That's what I was looking for a long time, periodically my shrimp are sucked from the outer filter. Stockings above the intake tube clogged constantly and let the filter does not work reliably, sponges look totally out prutschig. The pre-filter fits perfectly on my external filters, while still holding back large dirt particles and biologically filter as an additional internal filter. Who has less space, simply click on one chamber. A good, practical product.
